The present invention generally relates to light imaging arrays. More particularly, the present invention relates to light imaging arrays with data lines formed directly on the substrate.
Light-sensitive arrays for converting incident radiant energy into an electrical signal are commonly used in imaging applications, for example, x-ray imagers and facsimile device arrays. Hydrogenated amorphous silicon (a-Si) and alloys of a-Si are commonly used in the fabrication of photosensitive elements due to the advantageous characteristics of a-Si and the relative ease of fabrication. In particular, light-sensitive devices, such as photodiodes, can be formed in conjunction with necessary control or switching elements, such as thin-film transistors (TFTs), in relatively large arrays. As one skilled in the art will know, a thin-film transistor is comprised of thin layers on glass, where the glass acts only as a support, rather than doping of a silicon substrate.
X-ray imagers, for example, are formed on a substantially flat substrate, typically glass. The imager comprises an array of pixels with light-sensitive imaging devices, typically photodiodes, each of which has an associated switching element, such as TFTs. The array is addressed around its perimeter by a plurality of row and column scan lines having contact pads extending along the array. In operation, the voltage on the row lines, and hence the TFTs, are switched on in turn, allowing the charge on that scanned line""s photodiodes to be read out via the column scan lines, which typically include amplifiers. The row address lines are commonly referred to as xe2x80x9cscan linesxe2x80x9d or xe2x80x9caddress linesxe2x80x9d and the column address lines are referred to as xe2x80x9cdata linesxe2x80x9d or xe2x80x9cread-out lines.xe2x80x9d
Presently, the address lines are formed first on a bare substrate, typically glass, and the data lines are formed subsequently during the same process steps as the source and drain of the TFT switching element. As one skilled in the art will know, defects are more prevalent on later fabrication steps. Since the data line carries the image information, it is important for image quality that the data line be as reliable as possible. For this and other reasons, it would be helpful if the data line could be formed earlier in the fabrication process.
The present invention provides, in a first aspect, an exemplary imaging apparatus. The imaging apparatus includes a substrate, at least one light-sensitive imaging device disposed over the substrate, and a data line directly on the substrate coupled to the at least one light-sensitive imaging device.
The present invention provides, in a second aspect, an exemplary imager. The imager includes a substrate, an array of photodiodes vertically adjacent the substrate, at least one data line directly on the substrate, a plurality of switching devices coupled between the at least one data line and the array of photodiodes, and at least one addressing line coupled to the switching devices.
The present invention provides, in a third aspect, an exemplary method of forming an imaging apparatus. The method includes providing a substrate, forming a data line directly on the substrate, forming at least one light-sensitive imaging device vertically adjacent the substrate, and coupling the data line to the light-sensitive imaging device.
The present invention provides, in a fourth aspect, an exemplary method of forming an imager. The method includes providing a substrate, forming at least one data line directly on the substrate, forming an array of photodiodes vertically adjacent the substrate, forming a plurality of switching devices coupled between the data line and the array of photodiodes, forming at least one addressing line vertically adjacent substrate, and coupling the addressing line to the switching devices.